#include <iostream>
#define int long long
using namespace std;
const int MAX_COURS = 3e5+42, INF = 1e18;
int nbCours, nbSemaine;
int cours[MAX_COURS][2];
void input() {
cin >> nbCours >> nbSemaine;
for(int k = 0; k < 2; k++) {
for(int i = 0; i < nbCours; i++)
cin >> cours[i][k];
}
}
int calc(int petit, int grand) {
int rep = grand / petit;
if(grand % petit != 0)
rep++;
return rep;
}
int nbRestant[MAX_COURS];
bool possible(int k) {
int nbDispo = nbCours * nbSemaine;
for(int cur = 0; cur < nbCours; cur++) {
int truc = max(cours[cur][0], cours[cur][1]);
int nbUtilise = min(nbSemaine, calc(truc, k));
nbDispo -= nbUtilise;
nbRestant[cur] = k - nbUtilise * truc;
}
for(int cur = 0; cur < nbCours; cur++) {
if(nbRestant[cur] <= 0) continue;
nbDispo -= calc(cours[cur][1], nbRestant[cur]);
}
return nbDispo >= 0ll;
}
int dicho(int deb, int fin) {
while(deb < fin) {
int milieu = (deb + fin+1) / 2;
if(possible(milieu))
deb = milieu;
else
fin = milieu-1;
}
return deb;
}
signed main() {
input();
cout << dicho(0, INF);
}
